The present invention relates to a rasp blade hub assembly and in particular to improvements in the pins, the end plates, the means by which the end plates are secured together and the balancing of the hub.
Prior art rasp blade hub assemblies are made in a variety of configurations but typically are constructed from a pair of end plates sandwiching therebetween a core of rasp blades, spacers and pins formed into a stack loosely held in place by the pins. The hub assembly is fixed onto the shaft of a motor to drive the hub assembly. Rasp blade hub assemblies are used for the buffing of worn tires to remove the tread preparatory to resurfacing or retreading of the tire for further use.
According to a first aspect of the invention there is provided a rasp blade hub assembly pin, said pin having a hollow interior and a smooth exterior. Preferably, said pin has at least one open end.
According to a second aspect of the invention there is provided a method for securing together components of a rasp blade hub assembly including a plurality of rasp blades, spacers and rasp blade hub pins, each said pin having a hollow interior and a smooth exterior, each said pin extending through apertures in said rasp blades and spacers of said hub assembly and terminating in an aperture in an end plate of the said hub assembly, each said pin being secured frictionally within said aperture of said end plate by inserting a plug into said hollow interior of said pin and expanding said pin outwardly compressing the plug within said hollow interior of said pin to wedge said exterior of said pin within said aperture of said end plate.
According to a third aspect of the invention there is provided a rasp blade hub assembly including a first and a second end plate, each of said end plates extending between an outer and an inner radius, a stepped flange portion at said inner radius of each said end plate, a cylindrical sleeve having at one end a flange for cooperating with said stepped flange portion of one of said end plates while having a threaded portion at the opposite end of said cylindrical sleeve for engaging a nut accommodated within the stepped flange portion of said other of said end plates, whereby with rotation of said nut along said threaded portion said end plates are drawn together or loosened depending on the direction of said rotation.
Preferably, a rasp blade hub assembly includes a core of a plurality of spacers, rasp blades and locating pins assembled with the end plates and cylindrical sleeve according to the third aspect of the invention, applied to the core and the assembly secured together by tightening the nut on the cylindrical sleeve drawing the end plates together about the core. As in the prior art, a core includes a stack of rasp blades separated by spacer means, said rasp blades and said spacer means being arranged in annular rows, each row comprising a plurality of arcuate rasp blades or spacer means arranged about the longitudinal axis of said core, each said rasp blade and each said spacer means having a plurality of apertures therein for accommodating said pins therethrough. Each end plate has apertures for accommodating the pins holding the rasp blades and spacers of the assembly in alignment.
Preferably, each of the end plates has a series of holes or apertures in the end plate producing a ribbed or spoked appearance allowing circulation of air about the end plate as the assembly rotates. Preferably, the end plates are of a truncated conical shape. Preferably, each end plate has a ring affixed to the perimeter at the outer radius, said ring having the apertures for accommodating the pins holding the rasp blades and spacers of the assembly in alignment. Preferably, the pins are pins according to the first aspect of the invention.
According to another aspect of the invention there is provided a rasp blade hub assembly including a first and a second end plate, each of said end plates extending between an outer and an inner radius, a ring fixed to the perimeter at the outer radius of the respective end plates of the assembly, each said ring having apertures therein for accommodating pins therethrough when forming said rasp blade hub assembly. Preferably, each said ring has at least one enclosed cavity therein. Preferably, said cavity is located on the inner radius of said ring towards the said perimeter, extends along said perimeter and is filled with flowable or fluidic material, for example, liquid or powder such as sand to enable the hub assembly to be balanced in use. An aperture or apertures is (are) provided in the ring for filling or emptying said cavity or cavities. While a single circumferential cavity is preferred, a number of separate cavities arranged about the perimeter may be used. Preferably, said ring is a hardened steel ring and is secured to the outer perimeters of each of said end plates by adhesive bonding, by welding, or by any other suitable method within the knowledge of a person skilled in the art.
According to yet a further aspect of the invention there is provided a rasp blade hub assembly including:
a pair of end plates, each end plate extending between an inner and an outer radius with a stepped portion at said inner radius;
a cylindrical sleeve having at one end a stepped flange for engaging the stepped portion of one of said end plates and at said other end a screw thread, a nut locatable in the stepped portion of the other of said end plates and engaging said screw thread of said cylindrical sleeve whereby movement of said nut along said screw thread moves said end plates towards or away from each other;
a pair of rings, each ring fixed along the outer radius of each of said end plates, each said ring having a plurality of apertures for accommodating therein respective pins, each said ring having at least one enclosed cavity for accommodating a flowable mass;
a plurality of pins, each said pin being hollow and secured within a respective aperture of said ring by a plug, said pin being expandable upon compression of said plug within said hollow of said pin; and said plurality of pins holding components of a core in alignment, said core including a stack of rasp blades separated by spacer means, said rasp blades and said spacer means being arranged in annular rows, each row comprising a plurality of arcuate rasp blades and spacer means arranged about the longitudinal axis of said core, each said rasp blade and each said spacer means having a plurality of apertures therein for accommodating said pins therethrough.
According to an even further aspect of the invention there is provided a method of assembly of a rasp blade hub assembly, said hub assembly including a pair of end plates, each end plate being annular and extending between an inner and an outer radius and having a stepped portion at said inner radius;
a cylindrical sleeve having at one end a stepped flange for engaging the stepped portion of one of said end plates and at said other end a screw thread, a nut locatable in the stepped portion of the other of said end plates and engaging said screw thread of said cylindrical sleeve;
a pair of rings, each ring fixed along the outer radius of a respective said end plate, each said ring having a plurality of apertures for accommodating therein respective pins, each said ring having at least one enclosed cavity for accommodating a flowable mass;
a plurality of pins, each said pin being hollow and secured within a respective aperture of at least one of said rings by a plug; and said plurality of pins holding components of a core in alignment, said core including a stack of rasp blades separated by spacer means, said rasp blades being arranged in annular rows, each row comprising a plurality of arcuate rasp blades arranged about the longitudinal axis of said stack, each said rasp blade and each said spacer means having a plurality of apertures therein for accommodating said pins therethrough, said method including
a) forming said core by stacking a plurality of rasp blades in annular rows onto pins with each row separated by spacer means and made up of a plurality of arcuate rasp blades;
b) placing said core between said end plates with each end of said pins in an associated aperture of a respective ring;
c) inserting said sleeve so as to contact and extend between said inner radii of said end plates, applying a nut to said screw thread and tightening;
d) inserting a plug into the hollow interior of a pin, advancing said plug and compressing said plug in the region of said ring; and
e) repeating step d) for all pins.
According to yet another aspect of the invention there is provided a method for securing together components of a rasp blade hub assembly including a plurality of rasp blades, spacers and rasp blade hub pins, each said pin having a hollow interior and a smooth exterior, each said pin extending through apertures in said rasp blades and spacers of said hub assembly and terminating in an aperture in an end plate of the said hub assembly, each said pin being secured frictionally within said aperture of said end plate by inserting a plug into said hollow interior of said pin and compressing the plug within said hollow interior of said pin in order to wedge said exterior of said pin within said aperture of said end plate, each said rasp blade hub pin extending between a first and a second said end plate, each of said end plates extending between an outer and an inner radius, a stepped flange portion at said inner radius of each said end plate, a cylindrical sleeve having at one end a flange for cooperating with said stepped flange portion of one of said end plates while having a threaded portion at the opposite end of said cylindrical sleeve for engaging a nut accommodated within the stepped flange portion of said other of said end plates, whereby with rotation of said nut along said threaded portion said end plates are drawn together or loosened depending on the direction of said rotation.